1. Field of the Invention
The invention pertains to the field of optoelectronic devices. More particularly, the invention pertains to the field of optical links suitable for applications in long haul telecommunications, fiber-to-the home, radio over fiber, data communications and optical interconnects
2. Description of Related Art
There is a need in optical links operating at speeds above 20 Gigabit per second (Gb/s). Presently such links are realized by using power-consuming and expensive optical systems which include external modulators absorbing a significant power. For matching the needs of ever-growing serial transmission speed per wavelength per channel at low cost a new type of optical links is needed. However, the existing optical links based on standard devices suitable for data transmission rate up to 10-13 Gb/s include optical devices with a high capacitance exceeding 150 femto-Farads. It makes it difficult to realize high speed high quality data transmission in the optical link at low power consumption using these devices as the integrated circuits needed to drive this device require significant power.
A prior art optical interconnect (50) is shown schematically in FIG. 1. A modulator driver (1) representing an integrated circuit (IC) is electrically connected to the electrooptic modulator (2). The laser (3) provides lasing light of constant intensity which is modulated by electrooptic modulator (2). The electrooptic modulator (2) can be, for example, electrorefractive or electroabsorption modulator. Due to a high capacitance of the modulator device the power consumption of the driver IC is high, typically above 500 milliWatt (mW) and up to 10 Watt (W). The modulator driver is connected to the control IC (4) with a certain functionality, for example multiplexing/demultiplexing IC. The control IC (4) generates current pulses (10) that control the modulator driver (1). The modulator driver (1) generates current pulses (15) that cause the modulator (2) to modulate light. Light pulses (11) coming out from the modulator (2) are delivered from the modulator (2) by the optical waveguide (5).
The input light is delivered by the waveguide (6). The light pulses (21) delivered from the waveguide (6) come to the detector (7). The detector (7) transforms light pulses (21) into current pulses (20). Current pulses (20) are amplified by the amplifier (8). Amplified pulses of current (25) come to the control IC (4).
Various means can be used to deliver light. Light (9) from the laser (3) is delivered to the modulator (2), for example, through air or via optical system which may include lenses, optical isolators, waveguides and other elements. The current pulses (10) from the control IC (4) to the modulator driver (1) and the current pulses (20) from the from the detector to the amplifier are delivered via high frequency electrical lines.
Input (12) or output (13) pulses connect the electro-optic circuit (50) to the external devices for data acquisition. FIG. 1 shows only a part of the interconnect and a similar part is placed on the other end of the optical waveguide link. The optical waveguide link can be realized by, for example, plastic waveguide, duplex single mode fiber, duplex multimode fiber, fiber ribbon.